Bipolar articles and related methods

ABSTRACT

The invention provides bipolar articles (e.g., batteries and capacitors) with new architectures and methods of making and using the same. Articles are provided with interpenetrating anode and cathode structures that allow for improved power density, and arbitrary form factors that allow for formation in substantially any desired shape. The articles are useful for embedding or integral formation in various electronic devices to provide more efficient use of space in the devices. The articles optionally include self-organizing bipolar structures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/628,681 filed on Jul. 28, 2003 which claims priority to U.S.Provisional Application Nos. 60/398,902 and 60/399,050, both filed onJul. 26, 2002, which are herein incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to bipolar articles, such as batteries,and in particular to bipolar articles having interpenetrating currentcollectors and/or arbitrary form factors that are useful, e.g., forintegral formation or embedding in various electronic devices.

2. Summary of the Related Art

Batteries, and particularly rechargeable batteries, are widely used in avariety of devices such as cellular telephones, laptop computers,personal digital assistants, and toys. One example of a rechargeablebattery is a lithium solid polymer electrolyte rechargeable battery.This battery can be charged by applying a voltage between the battery'selectrodes, which causes lithium ions and electrons to be withdrawn fromlithium hosts at the battery's cathode. Lithium ions flow from thecathode to the battery's anode through a polymer electrolyte, and arereduced at the anode, with the overall process requiring energy. Upondischarge, the reverse occurs: lithium ions and electrons are allowed tore-enter lithium hosts at the cathode, while lithium is oxidized tolithium ions at the anode. This is an energetically favorable processthat drives electrons through an external circuit, thereby supplyingelectrical power to a device to which the battery is connected.

Currently available batteries typically have a layered design.Manufacturing constraints generally limit the available shapes or formfactors of these batteries. Common form factors include cylinders,button cells (thin discs), relatively thick (>3 mm) prismatic forms, andrelatively thin (<0.5 mm) prismatic forms. The relatively thickprismatic forms typically are made by rolling and pressing long coatedcathode and anode electrode assemblies separated by a thin separator, orby stacking or laminating layers of cathode/electrolyte/anode material.Some of these prismatic forms are made using a jelly roll or pressedcylinder process. The relatively thin (<0.1 mm) prismatic forms aregenerally made using thin film processes such as physical vapordeposition.

The energy density of these currently available batteries is relativelylow, due to poor volumetric utilization of space within devices in whichthe batteries are used. For example, short diffusion distances arerequired for lithium ion transport in a lithium battery. Therefore, thedistances between current collectors in a multi-laminate batterystructure is small, e.g., less than about 250 μm. The large number ofcurrent collectors reduces the volume and weight fractions ofelectroactive material in the battery. In addition, extra componentsgenerally are needed in the devices in which the batteries are used, inorder to allow the batteries to be inserted and connected. Suchcomponents include an internal chamber with suitable fit and finish forconsumer use, an extra set of interconnects to attach the battery to thedevice, and additional parts to allow the battery to be exchanged, suchas, e.g., a battery cover.

Therefore, a need exists for alternative battery designs that allow formore efficient use of space within electronic devices, and thus provideimproved power and energy densities.

Recently “three-dimensional batteries” have been proposed, which haveanodes and cathodes with active surface areas exposed in threedimensions. Such structures potentially can improve upon the resultsobtained using standard battery geometries by allowing for more optimaluse of materials through independent variation of the ionic andelectronic transport path lengths within the device. The presentinvention provides advances within the emerging field ofthree-dimensional batteries.

SUMMARY OF THE INVENTION

The present invention provides bipolar articles (i.e., articles such asbatteries and capacitors that have two poles, one positive and onenegative, that are electrically insulated from one another) having newarchitectures, such as interpenetrating anode and cathode structures,allowing for improved energy density, and arbitrary form factors,allowing for formation in substantially any desired shape. Such articlesare useful for embedding or integral formation in various electronicdevices to provide more efficient use of space in the devices. Some ofthe bipolar articles provided include self-organizing bipolarstructures, or sequentially assembled structures. Methods of making andusing the articles are also provided.

Accordingly, in one aspect, the invention provides a bipolar articlehaving an arbitrary form factor. The article includes a bipolarstructure having an anode, a cathode, and an electrolyte in contact withand separating the anode and cathode. The anode and cathode areinterpenetrating. The article further includes a cathode currentcollector that is in electronic communication with the cathode, and ananode current collector that is in electronic communication with theanode. The bipolar article has a desired arbitrary configuration. Theterms “arbitrary form factor” and “arbitrary configuration,” as usedherein with respect to a bipolar article as a whole, refer to a bipolararticle having an overall form that is not cylindrical or prismatic.“Prismatic” refers to a square or rectangular block having equalthickness across its length and width. In certain embodiments, a bipolararticle of arbitrary form factor has a thickness that varies across thelength and/or width of the article. In certain embodiments, a bipolararticle of arbitrary form factor has a thickness that varies over alength scale that is independent of any length scale of the internalelectrode structure of the article. In some instances, a bipolar articleof arbitrary form factor takes on the form of a device or housing inwhich it is contained, or some other conformal or complex shape, forexample, a shape including non-planar surfaces.

In another aspect, the invention provides a battery powered deviceincluding an interpenetrating electrode battery, which, in someinstances, is a self-organizing battery, a housing, and a mechanismpowered by the battery. The battery is integrated in the housing orformed in a cavity in the housing. In this context, “integrated” meansthat the battery is substantially space-filling within the housing.Particularly useful batteries are space-filling in a form factor that isneither cylindrical nor prismatic.

Still another aspect of the invention provides a bipolar articlecontaining first and second interpenetrating electrodes and a pluralityof first interpenetrating current collector features wired in paralleland in electronic communication with the first interpenetratingelectrode. The article further contains a second current collector inelectronic communication with the second interpenetrating electrode. Theplurality of first interpenetrating current collector features isdistributed through the thickness of the article. In some embodiments,the current collector features are spaced apart at distances and inlocations chosen to maximize power density. In certain embodiments, thecurrent collector features are spaced apart at distances and inlocations chosen to maximize energy density. For example, in a lithiumion (Li-ion) battery, adjacent current collector features are spacedapart at a distance greater than about 500 μm, in some instances greaterthan about 750 μm, or greater than about 1000 μm.

Another aspect of the invention provides a multi-layered Li-ion batteryhaving an energy density greater than about 212 Wh/kg.

Still another aspect of the invention provides a bipolar articleincluding a bipolar structure having an anode, a cathode, and anelectrolyte in contact with and separating the anode and the cathode. Atleast one of the anode and the cathode includes a lithium-containingelectroactive material. The article further includes a cathode currentcollector that is in electronic communication with the cathode, and ananode current collector that is in electronic communication with theanode. At least one of the anode and cathode current collectors includesone or more features projecting into the bipolar structure containingthe anode and the cathode. The minimum distance between adjacent currentcollectors is at least about 500 μm, in some instances at least about750 μm, and in certain instances at least about 1000 μm.

Another aspect of the invention provides a bipolar article including abipolar structure having an anode network and a cathode network, acathode current collector that is attractive to the cathode network andrepulsive to the anode network, and an anode current collector that isattractive to the anode network and repulsive to the cathode network. Atleast one of the anode and cathode current collectors is structured andarranged to reduce the effective thickness of the respective networkattracted thereto. The effective thickness is reduced by interweavingthe current collector through the bipolar article in such a way that theelectrical path length within the network is less than it would be ifthe current collector were not there. The location of the currentcollector balances the electrical and ionic conductivities of thesystem, as described in more detail below.

Yet another aspect of the invention provides a bipolar article includinga porous first electrode and at least one first current collector, atleast a portion of which is embedded within and in electroniccommunication with the porous first electrode. An electronicallyinsulating, ionically conductive material coats the pore structure ofthe porous first electrode. Within the pores of the coated porous firstelectrode is a second electrode having opposite polarity to the porousfirst electrode. A second current collector is in electroniccommunication with the second electrode.

In still another aspect, the invention provides a method of making abipolar article having an arbitrary form factor. The method includesproviding a first current collector in a mold having a configurationcorresponding to the desired arbitrary form factor, and depositing onthe first current collector a first electrode material, an electrolytematerial, and a second electrode material. At least one of the electrodematerials is configured to have one or more features projecting into theelectrolyte material and the other electrode material. A second currentcollector is provided on the first electrode, electrolyte, and secondelectrode materials.

Another aspect of the invention provides a method of making a bipolararticle having an arbitrary form factor, in which the arbitrary formfactor includes a thickness that varies across the length or width ofthe article. The method includes providing a first current collector ina mold having a configuration corresponding to the desired arbitraryform factor, and depositing on the first current collector a firstelectrode material, an electrolyte material, and a second electrodematerial. A second current collector is provided on the first electrodematerial, electrolyte material, and second electrode material. Themethod produces a bipolar article having a thickness that varies acrossthe length or width of the article.

Still another aspect of the invention provides a method of making alayered interpenetrating bipolar article. The method includes providinga first current collector and depositing on the first current collectoran electrode region. The electrode region contains an interpenetratingnetwork including an anode material, an electrolyte material, and acathode material. A second current collector is provided on theelectrode region. The foregoing method steps are repeated at least once.The method further includes electrically connecting the first currentcollectors with each other and with one of the anode or cathodematerials, and electrically connecting the second current collectorswith each other and with the other of the anode or cathode materials.

In yet another aspect, the invention provides a method of making aninterpenetrating bipolar article. The method includes providing a firstcurrent collector having at least one prong, and depositing on the firstcurrent collector an electrode region. The electrode region contains aninterpenetrating network including an anode material, an electrolytematerial, and a cathode material. The prong of the first currentcollector extends into one of the anode and cathode materials. A secondcurrent collector is provided on the electrode region.

Another aspect of the invention provides a method of making aninterpenetrating bipolar article. The method includes assembling a moldcontaining a first current collector and suspending a plurality ofsecond current collector mesh layers above the first current collectorin the mold. A self-organizing bipolar material is introduced into themold, so that the first and second current collectors are covered withthe self-organizing bipolar material. The self-organizing bipolarmaterial is cured to form interpenetrating anode and cathode networksseparated by an intervening electrolyte. One of the anode and cathodenetworks is attractive to the first current collector and repulsive tothe second current collector, and the other of the anode and cathodenetworks is attractive to the second current collector and repulsive tothe first current collector.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the following figures,which are presented for the purpose of illustration only and which arenot intended to be limiting of the invention.

FIG. 1 is a schematic illustration of an exemplary cell havinginterpenetrating electrodes.

FIG. 2 is a schematic illustration of a self-organizing batterystructure having an arbitrary form factor according to certainembodiments of the invention.

FIG. 3 is a schematic illustration of a battery structure embedded in adevice according to certain embodiments of the invention.

FIG. 4 is a schematic illustration of a self-organizing bipolar articleaccording to certain embodiments of the invention.

FIG. 5 is a schematic illustration of a stamping process for making abipolar article of arbitrary form factor with a self-organizing systemaccording to certain embodiments of the invention.

FIG. 5A shows a portion of the opposing electrodes enlarged toillustrate the arbitrary form factor.

FIG. 6A is a schematic illustration of a stamping process for embeddinga self-organizing battery in a device according to certain embodimentsof the invention.

FIG. 6B is a schematic illustration of a stamping process for embeddingan interpenetrating electrode battery in a device according to certainembodiments of the invention.

FIG. 7 is a schematic illustration of a multi-layered battery structureaccording to certain embodiments of the invention.

FIG. 8 is a schematic illustration of a method for making aself-organizing multi-layered battery according to certain embodimentsof the invention.

FIG. 9 is a schematic illustration of a battery structure withinterpenetrating current collectors according to certain embodiments ofthe invention.

FIGS. 10A-B are schematic illustrations of methods for making aself-organizing battery with interpenetrating current collectorsaccording to certain embodiments of the invention.

FIG. 11A is a schematic illustration of a self-organizing batterystructure with layered mesh current collectors according to certainembodiments of the invention.

FIG. 11B is an enlarged view of a portion of a mesh layer shown in FIG.11A.

FIG. 12 is a schematic illustration of a method for making aself-organizing mesh layer battery according to certain embodiments ofthe invention.

DETAILED DESCRIPTION

In general, factors associated with optimizing both energy and powerdensities in bipolar articles include (1) having a balanced cell withequal capacities of the anode and cathode, (2) having a maximum amountof active material (anode and cathode) in relation to electrolyte andpackaging, (3) establishing a minimum distance between the anode andcathode, and (4) establishing a maximum electrical conductivity withinthe anode and cathode network. In the past, attempts to increase theenergy capacity of a battery by increasing battery thickness andelectrode size have not been fully successful, because they often resultin reduced in power density. This is due to an imbalance that occursbetween the electronic and ionic conductivities in the battery system,because (i) the electronic conductivity decreases with the increasingbulk of the electrode, and (ii) the ionic conductivity decreases acrossthe electrode/electrolyte/electrode stack.

Traditional two-dimensional battery geometries (without interpenetratingelectrodes) are inherently unbalanced because ions (e.g. Li⁺) andelectrons flow in parallel directions, such that their transport pathlengths within the device cannot be independently adjusted. Such adesign does not allow for optimal use of materials, and generallyresults in an ionic transport path length that is longer than desired,and excess electronic conductivity in one or both electrodes. Incontrast, in “three dimensional batteries” having interpenetratingelectrodes with active surface areas exposed in three dimensions, thedirections of ion and electron flow are decoupled and can be adjustedindependently. This allows for better balancing of cell parameters bymore optimal use of materials, ultimately leading to improved cellperformance.

FIG. 1 illustrates an exemplary cell 100 having interpenetrating anodesand cathodes. For example, in a lithium ion system, the followingrelationship provides a balance of the two cell properties, electronicconductivity and ionic conductivity:σ_(e)˜1/(w ²/σ_(Li) ^(s) /l ² +w*a/σ _(Li) ^(e) /l ²)  (1)where σ_(e) is the electronic conductivity of the cathode 102 and anode104 electrodes in an interpenetrating system, σ_(Li) ^(s) is the ionicconductivity of lithium through the cathode 102 and anode 104electrodes, σ_(Li) ^(e) is the ionic conductivity of lithium through theelectrolyte 106, l is the length of the electrode extension 108, a isthe electrolyte thickness, and w is the width of the electrode extension108. One of skill in the art will appreciate that Equation (1) can bemodified accordingly if the ionic conductivity of lithium is differentthrough the cathode 102 and the anode 104. Thus, higher electrodeelectrical conductivities are necessary for larger lengths of electrodeextension. Accordingly, increasing the thickness of a battery structureto increase the energy capacity often is not feasible, because theresulting increased electrode thickness increases impedance and lowerspower density, and the electrical conductivity of the electrodes is notsufficient to allow high power densities.

Three-dimensional designs can be enhanced by spacing current collectorsthroughout the cell to balance the ionic and electronic conductivities,while minimizing the total current collector volume. The spacing betweencurrent collectors in a three-dimensional design can be greater than ispossible for a traditional two-dimensional design, because currentcollector placement is no longer dictated by ionic conductivity (i.e.,the ionic and electronic transport paths are decoupled). Thus, theinterpenetrating electrode structure of the three-dimensional designprovides greater power at any given current collector spacing. Forexample, a three-dimensional lithium ion battery of reasonable power canbe provided with distances between adjacent current collectors ofgreater than 500 μm, and in some instances greater than 750 μm, orgreater than 1000 μm. In comparison, one of skill in the art willappreciate that the current collector spacing in a two-dimensionallithium ion battery of comparable or lower power is generally no morethan about 200 μm to about 250 μm. Three-dimensional designs alsoprovide higher energy at a given power compared to two-dimensionaldesigns. By allowing for increased thickness with a reduced number ofcurrent collectors, an interpenetrating electrode battery providesequivalent power and higher energy density compared to a standardgeometry battery of the same size.

By way of example, a thick (e.g., greater than about 1 mm in thickness)interpenetrating electrode electrochemical cell is provided withmultiple current collectors that are wired in parallel and distributedthroughout the thickness of the battery. In general, the energy densityof a desirable cell is maximized for a specified rate capability.Because current collectors occupy space within the electrode assembly,in at least some instances it is desirable to reduce the number oflayers within the cell. However the rate capability of a cell isinversely proportional to its impedance or resistance. As a result, inat least some instances an optimized cell is one in which the number oflayers is minimized for a specified rate capability. In addition, thecycle life of a battery tends to be degraded if it is used at a ratecapability significantly above its design limit.

In an exemplary cell, the number of layers in the cell and the spacingbetween current collectors are chosen to satisfy the design parametersdescribed above with respect to Equation 1. The resistance ofinterpenetrating cells in the battery is modeled as a network ofresistors. In general, there are two cases for such layered cells:symmetric, in which each layer is uniquely served by a single pair ofcurrent collectors; and asymmetric, in which, for example, each layer isserved by a single cathode current collector, but multiple layers areserved by a single anode collector. A symmetric design generally issuitable for cathode and anode networks with similar levels ofresistivity, whereas asymmetric designs generally are more applicablefor cathode and anode networks with a large difference in resistivity.The model presented in this example is for symmetric designs, althoughalternative embodiments having asymmetric designs are also contemplated.The general relationship for the resistance of the cell is as follows:

$\begin{matrix}{R_{cell} = \frac{R_{layer}}{n}} & (2)\end{matrix}$where R_(layer) is the resistance of the layer and n is the number oflayers in the cell. In this example, R_(layer) is represented by thefollowing relationship:R _(layer) =R _(ccc) +R _(cccc) +R _(cn) +R _(electrolyte) +R _(an) +R_(acc),  (3)where R_(ccc) and R_(acc) are the electrical resistances of the cathodeand anode current collectors (CC), respectively, R_(cccc) is theresistance of the cathode current collector coating, R_(cn) and R_(an)are the electrical resistances of the cathode and anode networks,respectively, and R_(electrolyte) is the ionic resistance of theelectrolyte layer. A specific example of such a cell is set forth indetail in Example 1 below.

In general, because the electronic and ionic conductances are balancedin a three-dimensional battery with interpenetrating current collectors,the energy density of such a battery is greater than that of acorresponding two-dimensional battery. In some instances, energy densityperformance advantages are in the range of about 10%, about 25%, orabout 50%. For example, compared to a two-dimensional Li-ion batteryproviding an energy density of about 170 Wh/kg, a three-dimensionalLi-ion battery providing a performance advantage of about 25% would havean energy density of about 212.5 Wh/kg.

Arbitrary Form Factors

In some embodiments, the present invention provides a bipolar articleconstructed to have virtually any desired form factor or shape. Incertain embodiments, bipolar articles having arbitrary form factors areembedded in various devices such as, e.g., cellular telephones, personaldigital assistants, laptop computers, and the like, or are integratedinto a portion, e.g., a wall of a device. The efficient use of spacearising from arbitrary form factors provides for greater practicalenergy densities. Furthermore, bipolar articles having arbitrary formfactors advantageously allow for a reduced number of parts in devices inwhich they are used, thereby simplifying the design and reducing thecost of the devices. Relatively time-efficient and inexpensive methodsof making the bipolar articles described herein are also provided. Someparticularly useful bipolar articles include self-organizing structures.

FIG. 2 illustrates one non-limiting example of a battery with arbitraryform factor. The battery includes cathode and anode networks 200, 202separated by an electrolyte 204. Although not shown in the figure, insome embodiments, the networks 200, 202 are self-organizing and/or havean interpenetrating structure. In certain embodiments, the cathode andanode are sequentially assembled. The cathode and anode networks 200,202 are connected to respective cathode and anode current collectors206, 208.

FIG. 3 illustrates an example of a bipolar article of arbitrary formfactor that is embedded in a device. In the illustrated embodiment, abattery 300 and associated current collectors 302, 304 are embedded in adevice housing 306, effectively using available space in the device. Asanother non-limiting example, a very thin battery (e.g., about 1 mmthick) is embedded in the housing of a laptop computer behind the LCDdisplay. Such a battery extending to the full screen size of a typicaldisplay provides an energy density of about 600 Wh/l and a capacity ofabout 43 Wh. In alternative embodiments, batteries are embedded orintegrally formed in other spaces in laptops or other devices, such as,e.g., circuit boards or electronic components, such as DRAM chips.

In certain embodiments, a battery or other bipolar article of arbitraryform factor is produced using techniques such as, for example, coating,stamping, embossing, printing, or injection molding. One non-limitingexample of a method for making a bipolar article of arbitrary formfactor employs a direct writing process to build up layers with anarbitrary surface topology. For example, a battery is made by depositingindividual particles of anode, cathode, and electrolyte with apredetermined length, width and height onto an appropriate substrate.Layers are built up sequentially until the desired overall thickness ofthe battery is achieved. The battery is constructed so that (i) thecathode particles are interconnected to the cathode current collector,(ii) the anode particles are interconnected to the anode currentcollector, and (iii) the electrolyte separates the anode and cathodeparticles. Non-limiting examples of useful processes for forming thelayers of the device include ink jet printing, laser induced forwardtransfer, matrix-assisted pulsed laser evaporation, andphotolithographic techniques.

Multilayer coatings are well known in the manufacture of photographicfilms, with some film structures including as many as 15 distinctlayers. Such films are often manufactured using a coating process knownas simultaneous multilayer coating. In this process, multiple liquidlayers are simultaneously extruded from a slot coating head withmultiple dies onto an inclined plane and then onto a moving web.Intermixing between layers does not occur when the liquids aresufficiently viscous that their flow through the die slot and onto theinclined plane is of low Reynolds number (i.e., laminar flow). In someembodiments, a similar approach is used to make a bipolar article ofarbitrary form factor. For example, a 3-die slot head is employed, inwhich the lowest slot extrudes a cathode electrode slurry, theintermediate slot extrudes a separator/electrolyte, and the upper slotextrudes an anode slurry. Using cathode, anode, andseparator/electrolyte materials known in the art, a thin film battery isprepared in a single pass by coating cathode, separator/electrolyte, andanode layers onto a cathode current collector that has the desiredarbitrary shape, and laminating the dried coating to an anode currentcollector. In certain embodiments, repulsive forces between the anodeand cathode particles ensure that the coating operation, drying, andsubsequent lamination result in a thin film structure with no shorting,e.g., as described in more detail below.

Interpenetrating Current Collector Structures

In some embodiments, the present invention provides bipolar articleshaving geometries that reduce the electron transport pathway to thecurrent collector within an electrode, thereby increasing the electronicconductivity of the system and allowing the use of thicker batteries(e.g., greater than about 0.1 mm) without loss of power density (e.g.,power density greater than 300 W/kg and energy density greater than 450Wh/l). For example, certain embodiments provide thick batteries withinterpenetrating current collectors that have sufficient conductivityfor high power density. For a constant footprint, increasing thethickness of a battery increases its energy capacity, making it moresuitable for a wide range of applications. Moreover, bipolar deviceswith new architectures as described herein provide for high energy andpower density in a high capacity battery with relatively thin electrodelayers, thus avoiding the problems (e.g., long drying time) associatedwith thick, difficult to process electrode layers.

In some embodiments, the desired reduced electron transport path lengthis achieved via a bipolar article with interpenetrating currentcollectors. The interpenetrating structure of the current collectors(particularly the cathode current collector) increases theirconductivity, because the distance of electron transport through therelatively resistive electrode is reduced, thus allowing for thickbattery structures. The term “interpenetrating current collector” asused herein, refers to a current collector that extends some distanceinto one or more electrodes or electrode cells. The term “electrodecell” refers to an anode and cathode separated by an electrolyte. FIG. 7illustrates an example of a structure having interpenetrating currentcollectors extending into a plurality of electrode cells. FIG. 9illustrates an example of a structure having interpenetrating currentcollectors extending into electrodes.

Interpenetrating current collectors are provided using variousgeometries, for example, a current collector that projects into theelectrode or is interdigitated in two or three dimensions with the othercurrent collector (with intervening electrodes and electrolyte). In someembodiments, a reduced transport path length is achieved by use of aninterpenetrating current collector that projects into the body of thecorresponding electrode. The term “project,” as used herein with respectto current collectors, means that the current collector extends adistance outward from a plane defining the current collector and intothe corresponding electrode.

In certain embodiments, a reduced diffusion path length is achievedusing a bipolar device, e.g., a battery, with stacked electrode layerswith alternating anode and cathode orientations, and multiple surfacesof the current collectors in contact with the electrodes. These andother beneficial alternative structures with interpenetrating currentcollectors are described in more detail below. Further non-limitingexamples of useful geometries for interpenetrating current collectorsare as described in the following paragraphs for interpenetratingelectrodes.

In at least some embodiments, interpenetrating electrodes are used,which decrease the ionic transport distances between electrodes in adevice. Interpenetrating electrodes are described in detail ininternational patent application PCT/US02/23880, published as WO03/012908, which is incorporated by reference herein. The term“interpenetrating electrodes,” as used herein, refers to first andsecond electrodes configured such that that each electrode forms anetwork that is continuous in two or three dimensions, and eachelectrode extends into the other electrode to a distance greater thanthe smallest lateral dimension of the entities comprising the networks.By way of non-limiting example, in various embodiments, the twoelectrodes exhibit complementary geometries that form interlocking,infused, or interdigitated structures, or one electrode materialpermeates into voids or spaces in the other electrode material. In someembodiments, the nature of the interpenetration is such that the networkprovides multiple pathways to the current collector. In one class ofinterpenetrating structures, separation without a change in the shape orconnectivity of an electrode is prevented by the topology of theinterpenetrating network.

Due to their interpenetrating features, the two electrodes of thebipolar device approach one another very closely, while maintaining alarge interfacial area and decreasing the required volume ofelectrolyte. In some instances, the average thickness of the layer ofelectrolyte or separator between the electrodes is less than about 100μm, e.g., as low as about 1 μm. In certain embodiments, theinterpenetrating features of the electrodes have an average protrusionlength (corresponding to length l in FIG. 1) of about 10 μm to about5,000 μm. Such designs decrease the volume of the system by reducing thevolume that would normally be consumed by the separator, electrolyte,binder, conductive additive, and other inert components that, in someembodiments, do not store lithium.

By reducing the ionic transport distance between electrodes andpermitting independent variation of the electronic and ionic transportpath lengths within a battery, interpenetrating electrode structuresprovide similar power with larger spaces between current collectorscompared to typical battery geometries. The use of fewer, more widelyspaced current collectors in interpenetrating electrode batteries leavesmore room for electroactive material within a battery of a given volume,therefore providing a higher energy density than a standard battery ofthe same size.

Self-Organizing Systems

Some particularly useful bipolar devices having interpenetrating currentcollectors, arbitrary form factors, or both, include self-organizingsystems. Such systems are described, for example, in U.S. patentapplication Ser. No. 10/206,662, entitled “Battery Structures,Self-Organizing Structures and Related Methods,” filed on Jun. 26, 2002,which is incorporated by reference herein. That application describesthe use of various self-organizing structures to form bipolar devices(e.g., batteries), particularly those having interpenetrating cathodeand anode networks. Briefly, as described in that application,self-organizing systems used to form batteries and other bipolar devicescontain materials that exert attracting and repelling forces to produceinterpenetrating self-organizing structures. The same principle ofmutually repulsive and self-attractive surfaces is useful to organize abipolar device on a current collector.

FIG. 4 schematically illustrates an example of a self-organizinginterpenetrating bipolar device. The bipolar device includes a cathodestorage compound 400 (“material 1”) and an anode storage compound 402(“material 3”), which are both dispersed in an electrolyte 404(“material 2”). The materials 1 and 3 contact respective currentcollectors 406, 408. The materials 1, 2, and 3 are selected such thatwhen materials 1 and 3 are dispersed in material 2, materials 1 and 3repel each other. Also, the particles of material 1 self-attract andthereby aggregate, as do the particles of material 2. The system thusallows for the provision of self-organizing and separated cathode andanode networks. This allows for the formation of a self-organizing,co-continuous, interpenetrating microstructure, in which one electrodeis continuously wired to a current collector, and another electrode toanother current collector. A repelling dispersion force ensureselectronic isolation of the two networks.

The principles of surface forces are used in the organization of bipolardevices. Van der Waals (vdW) forces between molecules and condensedphases are composed of three contributions, a Keesom force due tointeractions between oriented permanent dipoles, a Debye force due topolarization induced in other molecules by a permanent dipole, and aLondon dispersion force due to polarization induced in other moleculesby oscillations in the electron cloud of interatomic bonds. Of these,the London dispersion force is the most universal, since it does notrequire the existence of permanent dipoles.

An important parameter scaling the dispersion force is the Hamakerconstant A. For symmetric combinations of materials (e.g., 121 or 212),the Hamaker constant A₁₂₁=A₂₁₂ is always positive, leading to anattractive dispersion force (F_(vdW)<0). For asymmetric combinations(e.g., 123), the dispersion force can be either attractive or repelling.For most materials, and especially low refractive index materials (n<2),the dominant interactions occur in the optical frequency range, and theHamaker constant can be approximated to good accuracy using opticalindex and static dielectric constant approximations as represented bythe following equation:

$A_{123} \equiv {{\frac{3}{4}{{kT}\left( \frac{E_{1} - E_{2}}{E_{1} + E_{2}} \right)}\left( \frac{E_{3} - E_{2}}{E_{3} + E_{2}} \right)} + {\frac{3}{8}\frac{{hv}_{e}}{\sqrt{2}}\frac{\left( {n_{1}^{2} - n_{2}^{2}} \right)\left( {n_{3}^{2} - n_{2}^{2}} \right)}{\left( {n_{1}^{2} + n_{2}^{2}} \right)^{1/2}\left( {n_{3}^{2} + n_{2}^{2}} \right)^{1/2}\left\{ {\left( {n_{1}^{2} + n_{2}^{2}} \right)^{1/2} + \left( {n_{3}^{2} + n_{2}^{2}} \right)^{1/2}} \right\}}}}$

The electronic frequency v_(e) corresponds to the mean ionizationfrequency of the materials present. Typically, v_(e)≈3×10¹⁵ Hz. k isBoltzmann's constant and h is Plank's constant. The refractive indicesin the visible range for mediums 1, 2, and 3 are n₁, n₂, and n₃,respectively. E₁, E₂, and E₃ are the static relative dielectricconstants. The first term in the equation gives the zero frequencyenergy of the van der Waals interaction, and includes the Keesom andDebye dipolar contributions. For two non-polar media acting over a thirdmedium, the first term is not significant.

When the indices are ordered as n₁>n₂>n₃, A₁₂₃ is negative. Thus, thesign and magnitude of the Hamaker constant can be readily estimated fromoptical and dielectric data, while more precise quantification, wherenecessary, is possible with full-spectral methods.

To provide a self-organizing system for two dissimilar materials 1 and 3separated by a medium 2, the vdW interaction is rendered repellingthrough judicious selection of materials characterized by a negativeHamaker constant A₁₂₃. Numerous combinations of materials 1, 2, and 3provide such a self-organizing system. Table 1 lists non-limitingexamples of some useful materials and combinations.

TABLE 1 Dispersion-Force Organized Systems System Material 1 (Cathode)Material 2 (Separator/Electrolyte) Material 3 (Anode) 1 LiCoO₂Poly(ethylene oxide) (PEO) or Mesocarbon microbeads (MCMB)or, Mg-dopedLiCoO₂ poly(ethylene glycol) (PEG) an unlithiated metal anode, such asSn, LiMn₂O₄ poly(styrene) (PS) Zn, Al, or Si, in each case coated with:LiMnO₂ poly(acrylonitrile) (PAN) POMA/PVDF or LiNiO₂ (each of the aboveoptionally POTh/PVDF doped with a lithium salt for Li⁺ conductivity) PEOor PVDF dissolved in a high refractive index solvent such asdiiodomethane, 1,3- diiodopropane, N,N- dimethylformamide (DMF),bromobenzene, cyclohexane, or dimethylpropylene urea (DMPU), the solventbeing subsequently evaporated and an organic liquid electrolyte beinginfused. 2 Cathodes as in System 1, Same as in System 1 Mesocarbonmicrobeads (MCMB) coated with: an unlithiated metal anode, such asPOMA¹/PVDF² Sn, Zn, Al, or Si POTh³/PVDF PEDT⁴/PTFE⁵ PEDT/PP⁶ PEDT/HDPE⁷3 LiFePO₄ Same as in System 1 Mesocarbon microbeads (MCMB) Li₂Fe₂(SO₄)₃,a lithiated metal anode such as Li, V₆O₁₁ LiAl, Li₃Al, LiZn, LiAg,Li₁₀Ag₃, V₂O₅ Li₅B₄, Li₇B₆, Li₁₂Si₇, Li₂₁Si₈, Li₁₃Si₄, Li₂₁Si₅, Li₅Sn₂,Li₁₃Sn₅, Li₇Sn₂, Li₂₂Sn₅, Li₂Sb, Li₃Sb, LiBi, or Li₃Bi 4 LiFePO₄Li₂OB₂O₃—Bi₂O₃ glass Mesocarbon microbeads (MCMB) Li₂Fe₂(SO₄)₃,Li₂O—B₂O₃—PbO glass a lithiated metal anode such as Li, V₆O₁₁ LiAl,Li₃Al, LiZn, LiAg, Li₁₀Ag₃, V₂O₅ Li₅B₄, Li₇B₆, Li₁₂Si₇, Li₂₁Si₈,Li₁₃Si₄, Li₂₁Si₅, Li₅Sn₂, Li₁₃Sn₅, Li₇Sn₂, Li₂₂Sn₅, Li₂Sb, Li₃Sb, LiBi,or Li₃Bi 5 Cathodes as in System 1, Same as in System 1 Mesocarbonmicrobeads (MCMB) coated with: an unlithiated metal anode, such asvanadium oxide Sn, Zn, Al, or Si hydrated vanadium oxide vanadiumoxide - PEO blend vanadium-boron- oxide vanadium-silicon- oxidevanadium- phosphorus-oxide ¹Poly(2-methoxyaniline) ²Poly(vinylidenefluoride) ³Poly(3-octylthiophene) ⁴Poly(3,4-ethylenedioxythiophene)⁵Poly(tetrafluoroethylene) ⁶Polypropylene ⁷High density polyethylene

Accordingly, in some embodiments, useful cathode and anode materialsinclude, but are not limited to, one or more of LiCoO₂,Li(Mg_(x)Co_(1-x))O₂, LiNiO₂, LiMn₂O₄, LiMnO₂, Li(Al_(x)Mn_(1-x))O₂,doped and undoped LiFePO₄, Li₂Fe₂(SO₄)₃, V₂O₅, V₆O₁₁, C, amorphouscarbon, graphite, mesocarbon microbeads (MCMB), Li, LiAl, Li₉Al₄, Li₃Al,Zn, LiZn, Ag, LiAg, Li₁₀Ag₃, B, Li₅B₄, Li₇B₆, Ge, Si, Li₁₂Si₇, Li, LiAl,Li₁₃Si₄, Li₂₁Si₅, Sn, Li₅Sn₂, Li₁₃Sn₅, Li₇Sn₂, Li₂₂Sn₅, Sb, Li₂Sb,Li₃Sb, Bi, LiBi, Li₃Bi, SnO₂, SnO, MnO, Mn₂O₃, MnO₂, Mn₃O₄, CoO, NiO,FeO, LiFe₂O₄, TiO₂, LiTi₂O₄, Sn—B—P—O compounds, and glass. Inparticular embodiments, an anode includes one or more of the followingmaterials: carbon, amorphous carbon, graphite, mesocarbon microbeads,Li, LiAl, Li₉Al₄, Li₃Al, Zn, LiZn, Ag, LiAg, Li₁₀Ag₃, B, Li₅B₄, Li₇B₆,Ge, Si, Li₁₂Si₇, Li₂₁Si₈, Li₁₃Si₄, Li₂₁Si₅, Sn, Li₅Sn₂, Li₁₃Sn₅, Li₇Sn₂,Li₂₂Sb₅, Sb, Li₂Sb, Li₃Sb, Bi, LiBi, and Li₃Bi, SnO₂, SnO, MnO, Mn₂O₃,MnO₂, Mn₃O₄, CoO, NiO, FeO, LiFe₂O₄, TiO₂, LiTi₂O₄, and glass. Incertain embodiments, a cathode includes one or more of the followingmaterials: LiCoO₂, LiCoO₂ doped with Mg, LiNiO₂, LiMn₂O₄, LiMnO₂, LiMnO₂doped with Al, doped and undoped LiFePO₄, LiMnPO₄, LixV₆O₁₃,Li₂Fe₂(SO₄)₃, V₂O₅, V₆O₁₁, and SnO₂.

In some embodiments, the separator/electrolyte medium 2 includes, but isnot limited to, one or more of the following materials, selected toprovide a repelling interaction or to wet between the cathode and anodematerials 1 and 3: organic materials, such as, e.g., poly(ethyleneoxide) (PEO), poly(styrene) (PS), poly(acrylonitrile) (PAN),poly(vinylidene fluoride) (PVDF), diiodomethane (DIM),1,3-diiodopropane, N,N-dimethylformamide (DMF), dimethylpropylene urea(DMPU), ethylene carbonate (EC), diethylene carbonate (DEC), dimethylcarbonate (DMC), propylene carbonate (PC), and block copolymer lithiumelectrolytes, the preceding organic materials being doped with a lithiumsalt, such as, e.g., LiClO₄, LiPF₆, LiAsF₆, LiHgI₃, LiCF₃SO₃ or LiBF₄,to provide lithium ionic conductivity; and inorganic materials, such as,e.g., LiI, LiF, LiCl, Li₂O—B₂O₃—Bi₂O₃ compounds including glass,Li₂O—B₂O₃—P₂O₅ compounds including glass, Li₂O—B₂O₃—PbO compoundsincluding glass, and sols or gels of the oxides or hydroxides of Ti, Zr,Pb, or Bi.

The cathode and/or anode materials 1 and 3 are optionally coated. Forexample, in certain embodiments a coating is provided on the cathodestorage compound or the anode storage compound in order to obtain arepelling dispersion force between the two in the separator/electrolytemedium. Non-limiting examples of useful coating materials includeelectronically conductive polymers and blends thereof, e.g.,polythiophene, polyanaline, poly(o-methoxyaniline) (POMA) orpoly(3-octylthiophene) (POTh) with PVDF, PEO, or conductive oxides suchas indium tin oxide (ITO). Some particularly useful coatings includepoly(3,4-ethylene dioxythiophene)(PEDT) or poly(3,4 ethylenedioxythiophene)-polystyrene sulfonate (PEDT-PSS) withpolytetrafluoroethylene (PTFE), PTFE derivatives, or PVDF.

A detailed description of useful coating materials is contained in U.S.patent application Ser. No. 10/354,405, entitled “Electrodes and RelatedDevices,” filed on Jan. 30, 2003, which is incorporated by referenceherein. For example, as described in that application, coatingsgenerally are selected to provide both the desired surface attractiveand/or repulsive forces and adequate conductivity for electrochemicaldevice function. Thus, the coating includes a conductive material, suchas, e.g., a conductive polymer or a copolymer or blend of conductivepolymers. Examples of conductive polymers include, without limitation,polyanilines (e.g., poly(2-methoxyaniline)), polythiophenes (e.g.,poly(3-octylthiophene) and poly(3,4-ethylene dioxythiophene)),polypyrroles, polyetheylenes, and derivatives thereof. Othernon-limiting examples of useful conductive materials include pureelements, such as carbon black, lithium, nickel, and zinc; metal oxides,such as vanadium oxide, indium tin oxide, titanium oxide, manganeseoxide, and nickel oxide; and metal sulfides. In some instances, thecoating material includes a dopant to improve conductivity. Suitabledopants include, but are not limited to, counter-ion sources such as,e.g., polystyrene sulfonate, hydrochloric acid, and lithiated compounds,tosylate ion, camphorsulfonic acid, dodecylbenzene sulfonic acid,perfluorodecane sulfonic acid, trifluoroacetic acid, and perchloricacid.

Some useful coatings also include a material with low refractive index,for example, to make the refractive index of the entire coating layerless than that of the electrolyte material being used. The amount of lowindex material in the coating is chosen to provide a desired averagerefractive index for the coating layer. Suitable low refractive indexmaterials include, but are not limited to, fluorinated polymers,polypropylene, and vanadium oxide. Non-limiting examples of fluorinatedpolymers include PTFE, PVDF, fluorinated esters of methacrylic acid(e.g., hexafluoroisopropylmethacrylate, heptafluorobutylmethacrylate,trifluoroethylmethacrylate, and pentafluorobutylmethacrylate),fluorinated esters of methacrylic acid, and copolymers and blendsthereof.

In some alternative embodiments, a separator/electrolyte material isselected to give a repelling dispersion force between the cathode andanode storage compounds, even in the absence of a coating. As anon-limiting example, the separator/electrolyte is an inorganic glassymaterial selected to have sufficiently high refractive index to providea repelling dispersion force between the cathode and anode compounds, aswell as sufficiently high lithium ionic conductivity and low electronicconductivity to act as an electrolyte.

To form a bipolar article, the self-organizing mixture is cured, and theanode and cathode networks are wired only to anode and cathode currentcollectors, respectively. One non-limiting example of a way to achieveproper wiring is to use surface forces on the anode and cathodeparticles for proper positioning. The principles that allow therespective networks to form and yet repel each other are used to wirethe networks to their respective current collectors. Each currentcollector has a surface that attracts either the cathode or the anodeand repels the other. In some embodiments, at least one of the currentcollectors is coated to provide the desired attractive and repulsiveforces. Useful coating materials include those described above forcoating anode and cathode materials. However, as one of skill in the artwill appreciate, somewhat different selection criteria apply forchoosing a coating for a current collector, as opposed to an electrodecoating. For a current collector coating, ionic conductivity is notrequired. Also, the electrical conductivity of the coating is lessimportant, because electrons need to travel through only a singlecoating layer to cross into the current collector. Furthermore, thickercoatings are suitable for coating current collectors, e.g., up to about1 μm coating thickness for a 10 μm thick current collector. Incomparison, particle coatings are generally thinner, e.g., up to about0.1 μm coating thickness for a 5 μm wide cathode particle.

For example, in some embodiments, London Dispersion Forces are used. Onecurrent collector is coated with a thin layer of a conductive lowrefractive index material, such as a conductive polymer blend, whichattracts low refractive index active materials (e.g.,appropriately-encapsulated LiCoO₂ particles) and repels high refractiveindex active materials (e.g., MCMB). The opposing current collector ischosen to have a high refractive index (e.g., pure Cu), which has theopposite attracting and repelling effects. In at least some embodiments,in order to make use of surface forces that are strong over relativelysmall length scales (less than about a few microns for London DispersionForces in most systems), the self-organizing composition is well-mixed,so that the anode and cathode particles are randomly and homogeneouslydistributed on a micron-level length scale.

Alternatively, fields such as gravity or magnetism are used to wire thecathode and anode networks to their respective current collectors, againby appropriate selection of materials. In the case of gravity, materialsare selected to provide a density contrast. As a non-limiting example,the density of the anode (e.g., MCMB) is less than that of thesolvent/electrolyte (e.g., DIM+PEO+Li salt), which is less than that ofthe cathode (e.g., LiCoO). In such a system the anode current collectoris above the cathode current collector.

Alternatively, a layered approach is used in conjunction with surfaceforces. In this approach, a thin (˜10× the active particle diameter)coating of an active material appropriate for connection to a currentcollector is coated sequentially in the immediate proximity of thecurrent collector and the self-organizing mixture. For example, a bottomcurrent collector is deposited, followed by a layer of the appropriateactive material, followed by a layer of self-organizing mixture of thenominal thickness of the cell layer, followed by a layer of the otheractive material, followed by the other current collector. Due to thehigh loading of the active materials (>˜50%), shorting does not result.

The following are non-limiting examples of specific architecturescontemplated for the bipolar devices as described herein, and specificmethods of producing such devices.

Methods of Making Interpenetrating Electrode Batteries Having ArbitraryForm Factors

A battery having virtually any desired form factor or shape is preparedwith interpenetrating electrodes, for example, using the self-organizingprinciples described above. Such batteries are useful to efficientlyutilize space in devices in which they are used. Suitable materials formaking the battery include, e.g., traditional battery materials used inthe field and self-assembling systems such as those described above.

Processes useful for making batteries or other bipolar articles ofarbitrary form factor with interpenetrating electrodes include, but arenot limited to, coating, stamping, embossing, printing, and injectionmolding. One non-limiting example of a stamping process, illustrated inFIG. 5, is as follows:

-   -   (1) Prepare a self-assembling mixture 500.    -   (2) Tape cast a cell precursor slab 505, for example, by tape        casting the self-assembling mixture 500 on a current collector        510.    -   (3) Stamp the mixture 500 with a form 520 while the mixture 500        is still viscous, optionally shaping one or both sides of the        mixture 500.    -   (4) Allow the stamped mixture 500 to self-assemble and cure,        forming anode and cathode networks 530, 540 with electrolyte 545        disposed there between.    -   (5) Form or attach a second current collector 550 to the battery        560.

FIG. 5A shows a portion of the opposing electrodes enlarged toillustrate the arbitrary form factor. The current collectors 510, 550optionally extend over the entire surfaces of the respective anode andcathode components. In alternative embodiments, current collectorsextend over only portions of the anode and cathode as illustrated inFIG. 2.

In some embodiments, interpenetrating electrode batteries are embeddedor integrally formed within various device, such as, e.g., cell phones,personal digital assistants, laptop computers, and the like. Variousprocesses are useful for embedding interpenetrating electrode batteriesin devices. For example, FIG. 6A illustrates a process in which aself-organizing battery is formed by stamping into a device as follows:

-   -   (1) Prepare a self-assembling mixture 600.    -   (2) Attach a first current collector 610 to a surface of a        device 620, e.g., within the device housing 630.    -   (3) Deposit the self-assembling mixture 600 on the first current        collector.    -   (4) Stamp the self-assembling mixture 600 to form fit the        desired surface topology.    -   (5) Attach a second current collector 640 to the surface of the        battery 650 opposite the first current collector 610.    -   (6) Allow the stamped mixture 600 to set.    -   (7) Apply a protective overcoat 660 to the battery 650.

Alternatively, the mixture 600 is injected into a cavity in the deviceand cured using the self-assembling principles described above.

FIG. 6B illustrates a similar process for making an interpenetratingelectrode battery with non-self assembling electrode materials bystamping into a device as follows:

-   -   (1) Prepare a cathode mixture 602.    -   (2) Attach a first current collector 610 to a surface of the        device 620, e.g., within the device housing 630.    -   (3) Deposit the cathode mixture 602 on the first current        collector.    -   (4) Stamp the cathode mixture 602 to provide a first reticulated        electrode.    -   (5) Coat the surface 604 of the stamped cathode mixture 602 with        an ionically permeable separator layer 606.    -   (6) Coat the ionically permeable separator layer 606 with an        anode material 608.    -   (7) Attach a second current collector 640 to the anode 608.    -   (8) Apply a protective overcoat 660 to the battery 650.

In certain embodiments, the separator layer 606 includes a Kynar-basedmaterial with a PVDF-rich binder.

Multi-Layered Battery

FIG. 7 illustrates one example of a multi-layered battery includingthree battery layers 700, 702, 704 separated by an anode currentcollector 706 and a cathode current collector 708. In the illustratedembodiments, the battery layers 700, 702, 704 are self-organizing. Eachlayer 700, 702, 704 includes self-organizing cathode and anode networks.In some alternative embodiments, non-self-organizing, e.g., sequentiallydeposited, layers are employed. Although not shown in the figure, insome embodiments, the anode and cathode networks are interpenetrating.The battery layers are oriented in an alternating arrangement such thatthe anode network of one layer faces the anode network of an adjacentlayer, and the cathode network of one layer faces the cathode network ofan adjacent layer. The battery layers 700, 702 are separated by thecathode current collector 708, which is in contact with the cathodenetworks of the layers. The battery layers 702, 704 are separated by theanode current collector 706, which is in contact with the anode networksof the layers. The cathode current collector 708 is electricallyconnected to an outer cathode current collector, and the anode currentcollector 706 is electrically connected to an outer anode currentcollector. In particular embodiments, the anode and cathode currentcollectors 706, 708 are electrically insulated from each other toinhibit shorting. In some instances, the battery layers 700, 702, 704each have a thickness of about 0.1 mm to about 5 mm, and the anode andcathode current collectors 706, 708 each have a thickness of about 0.005mm to about 0.05 mm. This allows for a high battery to current collectorratio, e.g., a ratio greater than about 10:1, and in some instancessignificantly greater than 10:1. A higher battery to current collectorratio provides higher energy density.

In some embodiments, a multi-layered battery is made by depositingmultiple battery layers on multiple current collectors. FIG. 8illustrates a non-limiting example of a method for making aself-organizing multi-layered battery as follows:

(1) Deposit a first layer of self-organizing material 810 on an outercathode current collector 800, and cure.

-   -   (2) Affix an anode current collector 820 on the first layer 810.    -   (3) Deposit a second layer of self-organizing material 830 on        the anode current collector 820, and cure.    -   (4) Affix a cathode current collector 840 on the second layer        830.    -   (5) Deposit a third layer of self-organizing material 850 on the        cathode current collector 830, and cure.    -   (6) Affix an outer anode 860 to the third layer 850.    -   (7) Electrically connect the anode current collectors 820, 860        to each other, and the cathode current collectors 800, 840 to        each other.

In some alternative embodiments, all of the layers 810, 830, 850 arecured at the same time, self-assembling into anode and cathode networksaccording to the self-organizing principles described above. In certainalternative embodiments, non-self-organizing anode and cathode materialsare employed.

Interpenetrating Current Collector with Projecting Elements

FIG. 9 illustrates an example of a battery with an interpenetratingcurrent collector structure. The battery includes a cathode currentcollector 900, an anode current collector 902, and a self-organizingbattery structure 904 disposed there between. The self-organizingbattery structure forms cathode and anode networks, which are in contactwith their respective current collectors. Although not shown in thefigure, in some embodiments the anode and cathode networks themselvesare interpenetrating. Each current collector 900, 902 includes aplurality of projecting elements or prongs 906, which extend into spaces908 between projecting elements of the other current collector 900, 902.By way of the prongs 906, each of the current collectors 900, 902penetrates into the self-organizing electrode assembly 904 for adistance that is less than the full dimensionality of the cell. Thecathode and anode current collectors 900, 902 have an interpenetratingarrangement, and define a serpentine gap there between. In somealternative embodiments, only one of the current collectors includesprojecting elements, and the other current collector has a planar orother structure.

FIG. 10A illustrates a non-limiting example of a method for making aself-organizing battery with interpenetrating current collectors asfollows:

-   -   (1) Deposit self-organizing material 110 on the first current        collector 112, which can be either the anode or the cathode        current collector.    -   (2) Position the other current collector 114 in an        interpenetrating arrangement with and spaced apart from the        first current collector 112.    -   (3) Cure the self-organizing material 110 to form cathode and        anode networks 116, 118 with electrolyte 117 disposed there        between. The networks 116, 118 are in contact with their        respective current collectors 114, 112.

One exemplary alternative method, illustrated in FIG. 10B, is asfollows:

-   -   (1) Arrange the anode and cathode current collectors 112, 114 in        a spaced-apart, interpenetrating arrangement.    -   (2) Introduce the self-organizing material 120 in the serpentine        gap 119 between the current collectors 112, 114.    -   (3) Cure the self-organizing material 110 to form cathode and        anode networks 116, 118 with electrolyte 117 disposed there        between. The networks 116, 118 are in contact with their        respective current collectors 114, 112.

One of skill in the art will understand that, while self-organizingmaterials constitute one particularly useful set of materials for makingbatteries with interpenetrating current collectors and other alternativebipolar structures described herein, such structures are also suitablyproduced using various non-self-organizing materials known in the field.For example, in some embodiments, a laminar approach is used, providinganode, cathode, and electrolyte layers on current collectors to form abattery having interpenetrating current collectors and/or arbitrary formfactors from standard battery materials known in the art.

Mesh Layer Structure

Another example of an interpenetrating current collector structureincludes an open or porous current collector that is inserted into anelectrode. For example, FIGS. 11A-B illustrate an example of a batterywith an open, e.g., mesh current collector. As shown in the side view ofFIG. 11A, the battery includes a first generally planar currentcollector 120, on which is a battery 122. In the illustrated embodiment,the battery 122 is self-organizing. One or more mesh layers 124 formingthe second current collector extend through the self-organizing battery122 at spaced-apart positions above the first current collector 120. Invarious embodiments, the mesh layers 124 form either the anode orcathode current collector. In some instances, the mesh layers are usedas the cathode current collector, because the electrical conductivity ofthe cathode network sometimes is not sufficient to provide high powerdensity in thick batteries. FIGS. 11A-B show the mesh layers forming thecathode current collector. FIG. 11B is an enlarged top view of a portionof one of the mesh layers 124. The mesh layers include a plurality ofopenings 126. The openings 126 are large enough to allow multiple anodenetwork elements or particles 128 and cathode network elements orparticles 129 to fit therein. For example, in certain embodiments, thecathode and anode elements or particles 129, 128 have a diameter on theorder of 2 μm, and the mesh spacing is greater than about 200 μm. Insome alternative embodiments, the cathode and anode elements orparticles 129, 128 have a diameter on the order of 200 μm, and the meshspacing is greater than about 20 mm. In the embodiment illustrated inFIG. 11B, the mesh 124 is attractive to and thereby in contact with thecathode network particles 129, and is repulsive to the anode networkparticles 128.

One non-limiting example of a method for making a self-organizing meshlayer battery, illustrated in FIG. 12, is as follows:

-   -   (1) Assemble a mold 130 having an anode current collector 132        and a plurality of spaced apart cathode current collector mesh        layers 134 suspended above the anode current collector 132.    -   (2) Introduce a self-organizing battery mixture 136 into the        mold 130 covering the current collectors 132, 134.    -   (3) Cure the self-organizing material 136, and remove the        battery from the mold 130.

In some alternative embodiments, a generally continuous manufacturingprocess is used in which the self-organizing material is continuouslydeposited on moving, continuous sheets of current collector material(i.e., layers of cathode current collector suspended over an anodecurrent collector). The self-organizing material cures while moving, andis cut in desired sizes. Such continuous manufacturing processes aresuitable for producing not just the present mesh embodiment, but alsovarious other device architectures described herein. Furthermore, asnoted above, self-organizing materials are useful, but variousalternative materials known in the field are suitable for producing themesh layered battery and other bipolar structures described herein.

Porous Electrode

Another example of an interpenetrating current collector structureincludes a current collector that is introduced into a porous electrode,which, in at least some instances, has an arbitrary form. In someembodiments, a battery with a porous electrode structure is provided. Afirst highly “open” porous electrode (e.g., sintered LMCO) is fabricatedwith pore diameters much greater than the primary particle size of thematerial to be used as the opposite electrode. This first structure isformed partially or completely of a storage electrode material by aprocess such as, for example, pressing, aggregation, or sedimentation ofparticles or coated particles into a preform mold of the desiredarbitrary shape, or stamping of particles or coated particles into thedesired arbitrary shape. Current collector(s) (e.g., having forms asdescribed elsewhere herein) are inserted into the porous network priorto such pressing, aggregation, etc. The particles are optionally heattreated or sintered to improve the strength and electrical conductivityof the porous structure. In some embodiments, a powder preform of thefirst electrode is formed into the desired arbitrary shape as a “greenbody” prior to sintering. Current collectors are embedded within thepowder preform and sintered in place. After sintering, the pellet withembedded current collectors optionally is etched to fully remove anycurrent collector from the pore space.

In some alternative embodiments, the porous structure is formed using aremovable pore-forming material, or phase-separation or precipitation ofthe constituents of the structure from a liquid or solid followed byremoval of a pore forming material. In other alternative embodiments, anactive material is directly fabricated as a foam. Further useful methodsfor forming the structure include, but are not limited to, lamination ofporous layers, layer-by-layer additive or subtractive depositionmethods, such as lithographic patterning and selective etching, andthree-dimensional printing of the structure material.

An electronically insulating, ionically conducting layer is formed uponthe surfaces of the first structure. For example, the insulating layeris an organic or inorganic solid electrolyte, or is a separator that issubsequently infiltrated with a liquid or solid electrolyte to provideionic conductivity. The insulating layer coats the internal and externalsurfaces of the first structure, and is formed by a method such as, forexample, infiltration of the first structure with the insulator in amolten form, infiltration of the first structure with a liquidcontaining the constituents of the electronic insulator, deposition ofthe insulator constituents from a vapor phase such as by chemical orphysical vapor deposition or plasma-enhanced deposition, reaction of thematerial of the first structure with a vapor phase or a depositedmaterial to form the surface insulating layer, electrolytic orelectrochemical deposition, or a combination of such methods. As anon-limiting example, the interior pore space and optionally the currentcollector penetrating into the pore space is coated with a precursor toan electrolyte (e.g., PEO+electrolyte salt mixture). The insulatinglayer is formed in one or in multiple process steps. The structure hassubstantially open porosity after the insulating layer is formed oninternal surfaces of the first structure.

The open porosity in the insulator-coated first structure is theninfiltrated with the second electrode material, or a composite mixturecontaining the second storage material, resulting in a secondinterpenetrating electrode that substantially occupies the pore space inthe first structure. The second interpenetrating electrode forms anelectronically conductive network, and is electronically isolated fromthe first electrode by an intervening electrolyte layer. In someembodiments, the first structure is infiltrated with a fluid comprisingthe second electrode material, and a reaction of the first structurewith the second electrode material or other constituents of the fluid isused to form an electrolyte layer. The second electrode material isinfiltrated, for example, as a melt, as a vapor phase species, byelectrolytic or electroless plating, as a liquid solution thatsubsequently dries or is reacted to form the second electrode material,or as a suspension of the second electrode material in a liquid.

In certain embodiments, a suspension of the second electrode material isused. The liquid in which the second electrode material is dispersed isoptionally a liquid or solid electrolyte, or contains a binder or theconstituents of an electrolyte in a solvent, or contains a material thatimproves the electronic conductivity of the second interpenetratingelectrode, such as, e.g., fine carbon or metal particles, or theconstituents of an electronically conductive polymer. As a non-limitingexample, a coated perform porous electrode is infiltrated with a mixtureincluding the opposite electrode material (e.g., MCMB), and optionally aprecursor to an electrolyte (e.g., PEO+electrolyte salt mixture), andoptionally a conductive additive to provide a supplemental currentpath—effectively acting as a current collector.

In some embodiments, a self-organizing system is used, in which secondelectrode particles and electrolyte materials are selected to exhibitthe desired attractive and repulsive forces. Thus, when the first porouselectrode structure is infiltrated with a suspension containing thesecond electrode material, a repulsive force results between the twoelectrode materials, causing their electronic isolation from each other.Accordingly, the electrolyte coats the walls of the first porouselectrode, while the second electrode accumulates in the interior porespace. The repulsive properties of first porous electrode and secondelectrode particles prevents the deposition of second electrodeparticles on the walls of the first porous electrode form, therebyavoiding shorting of the system.

After infiltration of the first porous electrode by the second electrodematerial and the attachment of a second current collector to thismaterial, a device comprising interpenetrating electrodes is obtained.In certain embodiments, the second current collector is inserted in theinterpenetrating electrode structure to create an interpenetratingcurrent collector. For example, in one such embodiment, a second currentcollector is used that has similar repulsive force characteristics asthe second electrode material.

The following non-limiting examples further illustrate certainembodiments of the invention.

Example 1

A thick symmetric electrochemical cell with interpenetrating electrodesis provided, with multiple current collectors wired in paralleldistributed throughout the thickness of the battery. The currentcollectors are configured in parallel by embedding them so that thecathode collector only connects to the cathode network and the anodecollector only connects to the anode network. The approximate spacingbetween current collectors and the number of layers in the cell arechosen by balancing design parameters as discussed in detail above withrespect to Equations 1-3. The interpenetrating current collectorstructure allows for a cell that provides similar rate capability withsignificantly fewer layers, and thus reduced current collector volume,compared to a standard cell, and significantly improved rate capabilityand life cycle compared to a three-dimensional battery with only asingle set of current collectors. The interpenetrating currentcollectors overcome the inherent shortcomings in electronic conductivityover large distances to allow for a battery with a thickness greaterthan 0.1 mm, a power density greater than 300 W/kg, and an energydensity of greater than 450 Wh/l.

The parameters of the cell are listed in Table 2 below. These parametersreflect a circuit in which charge moves through the cathode currentcollector across some fraction of the layer thickness of the cathodenetwork, across the electrolyte layer, across the complementary fractionof the layer thickness of the anode network, and through the anodecurrent collector for a number of layers in parallel. Some boundingestimates for the cell resistance are made. For example, the areafraction values assume a mesh with 67% open space along its length andthickness for the current collector layers, and assume that the areafraction is equivalent to the proportion of solids loading for thenetwork and electrolyte layers. The anode and cathode current collectorresistivities are known in the art, the anode and cathode networkresistivity values are based on measurements of a conventional cell, andthe electrolyte layer resistivity is based on the value for PEO at 40°C., which is known in the art. The area value for the electrolyte layerassumes a one-dimensional interpenetrating network with a 6 μm repeatdistance. The values in Table 2 reflect charge transfer halfway throughthe interpenetrating network (0.1 cm over a 0.2 cm full layerthickness).

TABLE 2 Cell Thickness (cm) Width (cm) Length (cm) Number of Layers 0.63.2 4.8 3 Thickness Area Resistivity Length Area Resistance LayerNetwork (cm) Fraction (Ω cm) (cm) (cm²) (Ω) Cathode Current Collector0.0025 0.33 2.60 × 10⁶ 4.8 0.003 0.005 Cathode CC Coating 0.0001 0.33100 0.0001 5.069 0.002 Cathode Network 0.2 0.33 3 0.1 5.069 0.059Electrolyte Layer 0.0002 0.31 500,000 0.0002 5.120 0.020 Anode Network0.2 0.36 0.5 0.1 5.530 0.009 Anode Current Collector 0.0025 0.33 1.70 ×10⁶ 4.8 0.003 0.003 Layer Resistance 0.094 Total Cell Resistance 0.031

The DC resistance (effectively equivalent to the AC impedance at 1000Hz) of the three-layer cell as shown in Table 2 is 31 mΩ for a 1.5 Ahcapacity. The effective DC resistance of conventional prismatic Li-ioncells is in the range of 30-50 mΩ for 0.8-2.0 Ah capacities,respectively. Thus, without major changes to the resistivities of thecathode and anode networks and the electrolyte layer, the three-layerinterpenetrating electrode system achieves effective DC resistances onthe order of those for conventional cells. The resistivity of thecathode current collector coating is substantially less than 10,000Ω cm.For a thin coating about 1 μm thick, a resistivity on the order of 100Ωcm contributes 2 mΩ to the total layer resistance. The cathode networkis generally the most resistive component of the cell.

The power density of conventional prismatic Li-ion cells is on the orderof 300 W/kg. Consideration of two factors indicates that the powerdensity of the cell described in Table 2 is at least about 300 W/kg.First, the effective DC resistance of the cell is 31 mΩ, a value on theorder of that measured for conventional cells with similar capacities.Second, polarization within the cell is the primary mechanismcontrolling power density. For conventional batteries, polarization isdominated by Li transfer through the relatively thick (on the order of100 μm) electrolyte layer. For the cell described in Table 2, theelectrolyte layer is relatively thin, on the order of 1 μm. Because therate of mass transfer is proportional to the square of the distance, thepower density of the cell described in Table 2 is significantly greaterthan that of a conventional cell.

Example 2

A self-organizing bipolar system, suitable for use in making articleshaving interpenetrating current collectors and/or arbitrary form factorsas described in Examples 3-8 below, is made using the components listedin Table 3.

TABLE 3 Cathode Current Al Collector Cathode CC Coating 10% PEDT-PSS (30nm) with 90% PTFE powder Cathode LMCO (3% MgO) (density ~5 g/cc)Encapsulant 10% PEDT-PSS (30 nm) with 90% PTFE powder Anode 6 μm MCMB(density 2.1 g/cc) Anode Current Cu Collector Electrolyte PEG + LiClO₄Solvent diiodomethane (DIM) + acetonitrile (AN)

Coated Cathode Current Collector

Aluminum (Al) disks are coated with a conductive polymer blend ofpoly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDT-PSS) andpolytetrafluoroethylene (PTFE) to function as the cathode currentcollector. This coating has a refractive index that renders itattractive to the cathode material, lithium magnesium cobaltate (LMCO),and repulsive to the anode material, mesocarbon microbeads (MCMB).

The coating solution is prepared with 10 wt % PEDT-PSS, available underthe trade name Baytron P from Bayer Corp. (one part poly(ethylenedioxythiophene) and 2 parts poly(styrene sulphonic acid)); 86.6 wt %Teflon from DuPont (Grade MP1100; narrow particle size distribution—1.5to 4 μm); 3.3 wt % nonionic fluorinated surfactant, Zonyl FSN fromDuPont (a perfluoroalkyl ethoxylated surfactant); and the balance water.1.45 g of a 1.3 wt % PEDT-PSS dispersion is placed in a glass vial witha magnetic stir bar. With agitation, 0.611 g water is added. After thisdilution, 126 μl of 5 wt % Zonyl FSN is added, followed by 145 μl ofN-methyl-2-pyrrolidinone. Finally, 0.163 g Teflon MP 1100 powder isadded, and the mixture is either agitated for at least 1 hour orsonified for 5 minutes. The resulting dispersion is 7.54 wt % solids.

The aluminum disks are prepared by taking extra heavy duty Reynoldsaluminum and punching out disks of 9/16 in. diameter. Each disk isflattened smooth and then rinsed in acetone for 2 min., followed byethanol for 2 min., and then dried. Each disk is then mounted on a glassplate using low tack adhesive, and the dull side of the disk is coatedby applying 50 μl of the coating dispersion. The disks are dried at 75°C. for 40 min., and then at 150° C. for 1 hour. The dried coatingthickness is 20 μm. The through conductivity is measured to be 5Ω (for acontact diameter of 0.25 in.), which corresponds to a volumetricconductivity of 1.26×10⁻³ S/cm.

Coated Cathode Material

The cathode material is lithium magnesium cobaltate (LMCO) having adensity of about 5 g/cc and a mean grains size of about 4 μm. Asdiscussed above, properties such as density are factors meaningful tothe gravitational settling of particles during self-organization. Grainsize is a factor for device stability, with particle size generallybeing chosen to be less than the device dimension in order to avoidshort-circuiting. The LMCO is encapsulated with a mixture of 90 wt %PTFE and 10 wt % PEDT-PSS by spray-drying, providing a conductivecoating of about 5 S/cm at a thickness of about 35 nm, representing avolumetric particle loading of about 5%.

A 1.3 wt % aqueous dispersion of PEDT-PSS, (particle size ˜30 nm,Baytron-PH, H. C. Starck) is mixed with an aqueous dispersion of PTFE(particle size 0.05-0.35 μm, Zonyl PTFE K-20, DuPont) that has beenfreed from surfactant by exhaustive dialysis against pure water. Aminimum amount of nonionic perfluorinated surfactant is then added toaid final dispersion stability. The PEDT-PSS/PTFE mixture is prepared sothat the ratio of solids PEDT-PSS:PTFE is 1:9. The volume of LMCO powderto be added to this mixture is calculated so that the volume ratio ofLMCO:(PEDT-PSS+PTFE) is 95:5. A volume of water equal to the calculatedvolume of LMCO is added to the PEDT-PSS/PTFE mixture to dilute it, andthen LMCO is added under high shear mixing to produce a well-dispersedmixture. The resulting mixture has a solids loading of about 50% byvolume, with mass ratios of LMCO:PTFE:PEDT-PSS of 95:4.5:0.5. Themixture is spray-dried to form LMCO particles encapsulated withPEDT-PSS/PTFE.

In another experiment, LMCO is encapsulated with a mixture of 90 wt %PTFE and 10 wt % PEDT-PSS by a mechanofusion process. LMCO, water,PEDT-PSS, and PTFE latex are mixed as described above, and the mixtureis subjected to a mechanofusion process. In this process, smallparticles of PTFE and PEDT-PSS are coated onto the surface of the LMCOparticles by the force applied to the particles as the mixture isrepeatedly passed through a narrow channel in a mechanofusion apparatus.This process also serves to make the particles more uniform in aspectratio.

Self-Organizing Slurry

The electrolyte is a solid polymer electrolyte including polyethyleneoxide (PEO) and lithium perchlorate (LiClO₄). In order to promoteself-organization, the electrolyte is dissolved in solution to which thesolid electrode components are added.

Poly(ethylene oxide) (PEO, 1 g, Polyox® WSR N80, Dow Chemical Co.,molecular weight 200,000), is dissolved in 10 ml of acetonitrile bystirring and heating in a closed container for 1 hour at 50° C. Then0.15 g of anhydrous lithium perchlorate is added to the solution (Li:Oratio 1:16) and stirred until the salt is completely dissolved; then 10ml of diiodomethane is added. The PEO-Li salt complex solution is usedto prepare a casting slurry by adding a predetermined amount of positiveand negative active materials.

The anode material, mesocarbon microbeads (MCMB) with a mean grain sizeof ˜5 μm, and the encapsulated LMCO cathode particles are mixed into thedissolved electrolyte in an anode to cathode capacity ratio of 1.05. Thesolids loading of the dried sauce is ˜70%. The MCMB is combined with theelectrolyte solution and magnetically stirred at ˜70° C. As soon as theMCMB is completely wet, the encapsulated cathode is added. The mixtureis magnetically stirred until well mixed at ˜70° C.

Example 3

A high surface area interface battery is made using a self-organizingmixture as described in Example 2. The heated self-organizing slurry isfed into a hopper of a stencil printer. Individual battery sections areprinted into stencils to provide a final battery stack that is 32 mmwide×48 mm long, with a thickness of 0.1 mm. The slurry is cast on aPEDT-PSS/PTFE-coated cathode collector as described in Example 2. Anopen mesh anode current collector is placed on top of the stencil. Aftervacuum curing, the energy density of the resulting symmetric cell about600 Wh/l. 23 sections are stacked with a thin mylar layer placed betweeneach one, providing a total battery thickness of 2.4 mm. The energydensity of the resulting symmetric cell is about 575 Wh/l.

In another experiment, 14 individual sections are stacked withalternating sections flipped, such that the cathode and anode currentcollectors of adjacent sections are in contact with each other and thetotal battery thickness is 3.5 mm. The energy density of the resultingsymmetric cell is 600 Wh/l.

Example 4

A self-organizing mixture as described in Example 2 is formed into abattery using injection molding. The heated mixture is injected atatmospheric pressure into a heated shaped preform with overalldimensions of about 30 mm×50 mm. The preform has three stepped layers.The bottom layer is 28 mm wide×48 mm long×2 mm deep, the middle layer is30 mm wide×50 mm long×2 mm high, and the top layer is 32 mm wide×52 mmlong×2 mm high. Prior to mixture injection, a current collector assemblyis placed in the preform in an alternating sequence of coated cathodecurrent collectors and anode current collectors. The current collectorshave dimensions that allow them to fit at close tolerance in theirrespective preform layers. They are held apart at a separation of 2 mmby an inert polymeric fixture. The current collectors are mesh, with a“hard” temper to prevent shorting during mixture injection. After curingat atmospheric pressure, the cells are removed from the preform and theterminals are connected to the exposed collectors at each layer. Theenergy density of the resulting symmetric cell is 600 Wh/l.

Example 5

A battery having an arbitrary form factor, with final dimensions about2×20×60 mm³ and a patterned lower surface, is made using an injectionmolding process. A self-organizing mixture as described in Example 2 isinjected into a perform having the desired arbitrary form factor. Priorto injection of the self-organizing mixture, a coated cathode currentcollector is pressed into a conformal shape on the bottom of the lowerpreform surface. After injection, an expanded metal anode currentcollector is placed over the mixture. The AC impedance at 1000 Hz isabout 125 mΩ and the power density is less than 300 W/kg. The energydensity of the final battery is 600 Wh/l, and its capacity is about 390mAh. The average separation between cathode and anode is about 2 μm.

Example 6

An embedded battery is made directly in the casing of a laptop computerusing stencil printing, with final dimensions of 1×300×240 mm³. Foursequential stencil prints are carried out, each 0.25 mm thick. Eachprint is carried out by first depositing a thin coated cathode currentcollector, printing a self-organizing mixture as described in Example 2,covering the printed mixture with a mesh anode current collector,curing, and covering the anode current collector with a mylar sheet. Thefour layers are wired in parallel, resulting in a 14.8 V battery. Theenergy density of the final battery is 600 Wh/l and its capacity isabout 2920 mAh. The AC impedance at 1000 Hz is about 2 mΩ and the powerdensity is greater than 4,500 W/kg. The average separation betweencathode and anode is 2 μm.

Example 7

A self-organized battery is made using tape casting. A heatedself-organizing slurry as described in Example 2 is tape cast onto aheated and coated cathode current collector to a thickness of 4 mm and awidth of 10 cm. An expanded metal anode current collector is held inposition midway through the thickness of the sheet, and extends outeither side of the 10 cm wide slab. Midway through the curing process,after the viscosity of the slab has increased and the repulsive forcesbetween anode and cathode are still operative, the slab is cut oncelength wise and periodically width wise to form cells with dimensions of5 cm×3 cm. An expanded metal coated cathode current collector is placedon top of each cell. After complete curing, cathode terminals areattached to either side of the cell and an anode terminal is attached tothe extended current collector. The energy density of the symmetric cellis 600 Wh/l.

Example 8

A battery with final dimensions 6×32×48 mm³ is made according to a tapecasting process as described in Example 7. The battery has two expandedmetal coated cathode current collectors and two expanded metal anodecurrent collectors. The current collectors are equi-spaced through thethickness of the cell, creating three layers that are each 2 mm thick.The AC impedance at 1000 Hz is ˜31 mΩ and the power density is greaterthan 300 W/kg. The energy density of the final battery is 600 Wh/l andits capacity is about 1495 mAh. The average separation between cathodeand anode is 2 μm.

As will be apparent to one of skill in the art from a reading of thisdisclosure, the present invention can be embodied in forms other thanthose specifically disclosed above without departing from the spirit oressential characteristics of the invention. The particular embodimentsof the invention described above are, therefore, to be considered asillustrative and not restrictive. The scope of the invention is as setforth in the appended claims, rather than being limited to the examplescontained in the foregoing description.

The invention claimed is:
 1. A bipolar article, the article comprising:(a) a housing comprising an inside surface and an outside surface;wherein the inside surface has an arbitrary form factor which isindependent of the form factor of the outside surface and is notcylindrical or prismatic; (b) a bipolar structure comprising a cathodecurrent collector, an anode current collector, an anode, a cathode, andan electrolyte in contact with and separating the anode and cathode;wherein the anode and cathode are interpenetrating; the cathode currentcollector is in electronic communication with the cathode; and the anodecurrent collector is in electronic communication with the anode; whereinthe bipolar structure as a whole has an arbitrary form that is notcylindrical or prismatic; and at least one of the cathode, the anode,and their respective current collectors has an arbitrary form that isnot cylindrical or prismatic and is conformal to the inside surface ofthe housing.
 2. The bipolar article of claim 1, wherein the housing isan outer casing of the bipolar article.
 3. The bipolar article of claim1, wherein the housing is a housing of a battery powered device.
 4. Thebipolar article of claim 1, wherein the anode, electrolyte, and cathodeare sequentially deposited.
 5. The bipolar article of claim 1, whereinthe bipolar article is a battery.
 6. The bipolar article of claim 1,wherein the anode includes one or more materials selected from the groupconsisting of carbon, amorphous carbon, graphite, mesocarbon microbeads,Li, LiAl, Li₉Al₄, Li₃Al, Zn, LiZn, Ag, LiAg, Li₁₀Ag₃, B, Li₅B₄, Li₇B₆,Ge, Si, Li₁₂Si₇, Li₂₁Si₈, Li₁₃Si₄, Li₂₁Si₅, Sn, Li₅Sn₂, Li₁₃Sn₅, Li₇Sn₂,Li₂₂Sn₅, Sb, Li₂Sb, Li₃Sb, Bi, LiBi, and Li₃Bi, SnO₂, SnO, MnO, Mn₂O₃,MnO₂, Mn₃O₄, CoO, NiO, FeO, LiFe₂O₄, TiO₂, LiTi₂O₄, and glass.
 7. Thebipolar article of claim 1, wherein the cathode includes one or morematerials selected from the group consisting of LiCoO₂, LiCoO₂ dopedwith Mg, LiNiO₂, LiMn₂O₄, LiMnO₂, LiMnO₂ doped with Al, doped andundoped LiFePO₄, LiMnPO₄, LixV₆O₁₃, Li₂Fe₂(SO₄)₃, V₂O₅, V₆O₁₁, and SnO₂.8. The bipolar article of claim 1, having a power density greater thanabout 300 W/kg.
 9. A device comprising the bipolar article of claim 1.10. The device of claim 9, wherein the arbitrary form factor of thebipolar article is conformal with at least one surface of the device.11. The device of claim 9, wherein the device has a cavity, and whereinthe arbitrary form factor of the bipolar article is space-filling withinthe cavity.
 12. The device of claim 9, wherein the device is a cellulartelephone, laptop computer, personal digital assistant, or toy.